A legitimate IMEI repair would only be possible if a phone's original, correct IMEI was corrupted due to a software crash (rare on modern Qualcomm devices). Almost all tools marketed as "IMEI repair" are used to write a different number, not restore the original.
: While repairing a corrupted original IMEI is generally legal for personal use, altering an IMEI to a different number is illegal in many jurisdictions. Hardware Risk A legitimate IMEI repair would only be possible